A Case Series of Steroid-Responsive Encephalopathy Associated With Autoimmune Thyroiditis (SREAT) With Atypical Thyroid Lab and Imaging Findings.

Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT) is a rare, potentially reversible neuropsychiatric syndrome linked to autoimmune thyroid disease. However, its clinical heterogeneity may stray from the most accepted diagnostic criteria often leading to a delay in its recognition. In this paper, we describe two patients who presented with subacute encephalopathy for which the diagnosis of SREAT was established after the detection of elevated antithyroid antibody titers and the exclusion of alternative etiologies. Notably, both cases exhibited atypical features, namely CSF lymphocytic pleocytosis and leptomeningeal enhancement in Case 1 and a complex differential confounded by multiple comorbidities in Case 2. Treatment strategies included corticosteroid-based immunosuppression, with one patient also receiving intravenous immunoglobulin and thyroid hormone replacement. Both patients demonstrated substantial neurological improvement following therapy, underscoring the reversibility of this condition when appropriately treated. Together, these cases highlight the importance of maintaining diagnostic suspicion for SREAT in patients with unexplained encephalopathy, even in the absence of overt thyroid dysfunction, atypical lab and imaging findings, and a complex past medical history. Early recognition and initiation of immunotherapy can significantly alter outcomes and prevent prolonged morbidity. By presenting these cases, we aim to add to the limited body of literature on SREAT and emphasize the critical role of maintaining suspicion for SREAT in atypical cases of probable autoimmune encephalitis to facilitate timely diagnosis and intervention in optimizing patient recovery.